Consumers continue to demand computer systems with higher performance and lower cost. To address these challenges, integrated circuits are designed as systems on chips (“SoCs”) and include an increasing number of modules, such as central processing units (“CPUs”), advanced processing units (“APUs”), graphics processing units (“GPUs”), memory sub-systems, system controllers, and complex peripheral functions. At the same time, gaining visibility into the operation of the system and determining that the system is operating as desired is increasingly difficult. The complexity and cost of finding and eliminating functional “bugs” provide significant challenges. Also, generating, storing, and analyzing the data required to determine if the defects are generally within the system, within a specific module, or between a set of modules present a significant challenge. These challenges become more difficult when it is important to analyze the operation of one circuit operating in one clock domain based on an event or set of events that take place in a different circuit that operates in a different clock domain that is asynchronous to the first circuit's clock domain.
In the following description, the use of the same reference numerals in different drawings indicates similar or identical items. Unless otherwise noted, the word “coupled” and its associated verb forms include both direct connection and indirect electrical connection by means known in the art, and unless otherwise noted any description of direct connection implies alternate embodiments using suitable forms of indirect electrical connection as well.